fix(android): use the heart icon for favorite in Now Playing (was a star)

Every other favorite toggle uses Favorite/FavoriteBorder (heart); Now Playing
was the odd one out with Star/StarBorder. Make it a heart everywhere.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

android/app/src/main/kotlin/com/novasonic/app/ui/screen/NowPlayingScreen.kt

@@ -322,7 +322,7 @@ fun NowPlayingScreen(
                                     .clickable(onClick = onStarToggle),
                             ) {
                                 Icon(
-                                    if (starred) Icons.Default.Star else Icons.Default.StarBorder,
+                                    if (starred) Icons.Default.Favorite else Icons.Default.FavoriteBorder,
                                     null,
                                     tint = if (starred) NsAccent else Color.White.copy(0.5f),
                                     modifier = Modifier.size(22.dp),